[2019.06.24 study notes 1]
1. Define client-side script (such as JavaScript);
2. Include a script file
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset=“UTF-8”>
<title>标题 </title>
<script type="text/javascript">
alert("弹出框");
</script>
</head>
<body>
</body>
</html>
3. The introduction of an external script
html file
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset=“UTF-8”>
<title>标题 </title>
<script type="text/javascript" src="index.js"></script>
</head>
<body>
</body>
</html>
javascript file
alert ( "pop-up");